Although Donald Trump says he’d bring back waterboarding as an interrogation technique as commander in chief, claiming, “Only a stupid person would say it doesn’t work,” intelligence veterans debate the practice in a Thanksgiving-weekend Showtime doc, “The Spymasters: CIA in the Crosshairs.”

The film includes interviews with 12 CIA chiefs. Gen. Michael Hayden, director under George W. Bush, says: “If some future president is going to decide to waterboard, he’d better bring his own bucket, because he’s going to have to do it himself.”

Also explored is whether 9/11 was due to an intelligence failure. Current CIA director John Brennan says in the film: “I wish the world were simple.”